Some time ago there was a thread about battery charging via (if I remember correctly) a rather small device which stayed connected to the batter. I have done a search but cannot find it. Can you help please?
I think it was a modern type of charger which uses pulses to prevent sulphide forming on the battery plates. There is some well known US company making them (not cheap) and I have a German one at home which worked great on an old Concorde (ex-TB20) battery. I can dig out the names tonight if somebody else doesn’t post them.
However I even bought a cheap (£50) charger from Halfords which uses pulses. It just…. didn’t work if the battery was too flat. It would never “lift it up”. Not even after days. Completely useless.
The Solar panels are great and would be particularly good for a non-generator antique with a battery to power the radio.
Securing them is not an easy matter though. I suppose, in an emergency situation (left the Master switch or the courtesy light on) and on an airport which has proper AK47 security, one would duct-tape them to the top of the wing.
The company which made the ones in my pic (they are particularly good – bought 10 years ago) has vanished but there are some others. My ones will even power a 24V (25W) soldering iron. Obviously anything less than full sunlight does sod-all; even a bright overcast drops the output to 10% i.e. useless for charging but fine for preventing a battery going flat.
The US product is BatteryMINDer 24041 and I recall there is an “EU” version with a 230V input.
The German product is CTEK MXT 4.0. I have one here. It works great.
CTEK is a Swedish company. Their devices have a great reputation among owners of classic cars and motorbikes. I keep a CTEK MXT 4.0 always connected to my aircraft battery. The adapter to connect it to the aircraft battery is included, you only need to add an inline fuse.
15 hours of sunshine? And that probably only works if the panels are always rectangular to the sun rays. Maybe invent a contraption with an electric motor that always turns the panels into the right angle … and use the solar power for that :-)) Perpetuum mobile?
(Good device for England anyway :-) Wouldn’t a rain-generator be better? :-))
I think the vendor that got the product going originally was Battery Tender (Deltran), and in some places that has become the informal name for any such full time connected charger. They do make 220 V EU market devices – I bought one. Availability from any company becomes more limited moving from 12 VDC output to 24 VDC output. I own some indeterminant number of Battery Tenders, maybe seven or eight, and they’re connected full time. I’ve had no problems leaving all of them connected and unattended for years.
The solar panels I show are two “24V” models in series so the open-circuit voltage is “48V” – actually more like 70V in bright sunlight.
Electrical theory dictates that maximum power transfer takes place when the on-load voltage at the output terminals is 50% of the open circuit (no load) voltage, which is why I did it that way. A solar panel whose no-load voltage is say 28V would transfer almost no power into the battery.
I don’t think anything bad happens at night i.e. the solar panels don’t drain the battery, but I don’t recall if this is true, and anyway I put a diode in series. The diode drop is about 0.6V so insignificant on this scale.
My point was that 2 sunny days would probably charge the battery pretty well, and one such day might charge it enough to start the engine – with the usual caveat about not doing this if departing into IMC, or departing at any time with a DA42 
Not much chance right now
EGKK 111658Z 1118/1224 25012KT 9999 SCT040 PROB30 TEMPO 1118/1121 22015G25KT 4000 SHRA BKN012 BECMG 1200/1203 19015G25KT TEMPO 1205/1218 6000 RA BKN015 BECMG 1209/1212 18030G45KT PROB40 TEMPO 1213/1218 3000 +RA BKN012 BECMG 1216/1219 23018G28KT
but it might work elsewhere
LGIR 111700Z 1118/1218 18012KT 9999 FEW020
Well, you are the engineer here, I know :-) But whenever I experimented with solar panels it was frustrating. I tried one of those sets that claim they can charge a cellphone. I remember how i put it on our TERRACE IN LGIR (yes,, Peter I have a terrace in LGIR, want to go? ;-)) in August, 40° and after hours it had charged like 1 percent. Would have charged the battery if I had put it in the sunlight even without the solar panel ;-))
Those phone chargers are crap.
I have one somewhere.
It might work on Planet Mercury (on the sunny side), with the Nokia 6310i but a modern smartphone draws something like 1 amp, perhaps briefly, and that causes the panel’s output to collapse completely.
The phone’s power supply is a switching power supply which means as the input voltage falls it draws more current (i.e. a negative resistance) and that plays havoc with solar panels, which unless mega over-specced just collapse to almost nothing, then the phone’s power supply shuts down, then it restarts and again draws the 1 amp or whatever, so the cycle repeats.
The panels in my pic output 1 amp into a 24V battery. So with a suitable power transfer optimised regulator you could get a 5V “USB” power output at about 4A max. That would charge an Ipad.
Now compare the surface area against your solar charger
Yes, I know, I was only kidding you :-) I know that this is something more professional
Many PA46 owners including myself use BatteryMinder. I have been using it with good results for the past 6 years.
Rocket Engineering provide SB50 connectors for charging hookup in the nose compartment as part of the Jetprop conversion.
I have the 24v European version, and I have just bought the latest S5 version which has been optimized for Concorde batteries. I will use this version at a new hanger I am establishing in Phuket.
Given the lack of GPU availability, I rely on battery starts, and my batteries have to be perfect to prevent damage to the turbine during starting.
E
